Fluid pressure braking system



Patented Apr. 29, 1941 2,239,613 FLUm PRESSURE Bmxmc. SYSTEM Owen H. Fowler, Detroit, Mich., asslgnor to Bydraulic Brake Company, Detroit, Mich., a corporation of California Application June s, 193s, serial No. 212,179

(c1. cio-54.6)

12 Claims.

ing a cylinder having therein a fixed piston dividing the cylinder into a reservoir and a compression chamber. 'Y Y Another feature of the invention is a pressure producing device of the compound type including telescopic cylinders, one having therein a xed piston and the other having therein a reciprocable piston.

Another feature of the invention is to provide a fluid pressure device including a cylinder, a

piston reciprocable in the cylinder having on its heada sealing cup, and means for by-passing uid past the piston to compensate for expansion and contraction ofthe fluid so constructed and arranged as to avoid injury to the sealing means.

Other objects and features of the invention will appear from the following description taken in connection with the accompanying drawing forming a part of this specification, and in which- Fig. 1 is a diagrammatical illustration of a fluid pressure braking system embodying the invention; I

Fig. 2 is a vertical sectional view of the pressure producing device illustrated in retracted position;

Fig. 3 is a sectional view substantially on line 3-3, Fig. 2;

Fig. 4 is a fragmentary sectional view illustrating the pressure producing device on its compression stroke.

In the drawing, I8 represents a fluid pressure producing device including a cylinder I2, open at one end and closed at its other end by ahead adjacent the flange is a groove 22 for attaching a flexible dust shield 24. The cylinder also has arranged in its wall on the interior thereof a plurality of spaced slots 26, preferably semielliptical. vThese slots are arranged in a circle, and are suitably spaced from the open end of the cylinder.

A piston 28 reciprocable in the cylinder I2 is held against displacement by a retaining ring 38 seated in a groove 32 in the wall of the cylinder adjacent the open end thereof. The piston has a head 34, a reduced body portion 36 providing in conjunction with the wall of the cylinder an annular chamber 38, and a skirt 4I] :supporting a concentric rod 42 channeled as indicated at 44 and provided with a reduced end 46. AThe head 34 has a plurality of spaced pas-- sages 48 therethrough providing communications of the cylinder.

A sealing cup 52 on the head of the piston controls the passages 48 in the head, and a spring 54 interposed between the sealing cup 52 and the two-,way valve I8 serves to retain the cup and valve against displacement and also to return the I4 having a discharge port I6 controlled as by a two-way valve I8. The cylinder has on its wall adjacent the closed end thereof of a radial flange 28 for mounting the cylinder in a fixed upright position, and arranged in the wall of the cylinder piston toits retracted position. When the piston is in its retracted position, it seats on the retaining ring 38 with its head and the sealing cup 52 thereon intermediate the overall length of the slots 26, so that iluid in the cylinder` may freely by-pass the piston.

A cylinder 56, open at one end and closed at its other end as by a head 58, has in its head. a filling opening 60 normally closed by a plug 62 having a socket 64, the purpose of which will hereinafter appear, and a plurality of openings 66 through the plug for venting the cylinder to the atmosphere. The cylinder 56 is mounted for reciprocation on the cylinder I2, and movement of the cylinder 56 is limited by a stop 68 mounted in the wall thereof and received by a slot 10 in the wall of the cylinder I2. The cylinder 56 has in its wall adjacent its open end a groove 12 for the attachment of the flexible dust shield 24, and a sealing cup" `l4 seated on the open end of the cylinder I2 with its lip engaging the wall'of the cylinder 56 linhibits seepage of fluid between the cylinders.

The cylinderl 56 has an internal shoulder 16,

and seated on this shoulder is a fixed piston 18 dividing the cylinder into a compression chamber 80 forward of the piston and a reservoir 82 back of the piston. A sealing cup 84 seated on the piston and engaging the wall of the cylinder inhibits seepage of fluid past thepiston, and aI spring 86 interposed between the cup 484 and the cup 14 carried by the cylinder Ilv serves to retain the cups in position and also to return the cylinder 56' to its' retracted position wherein it.

seats on the stop 68.

iThe fixed piston 18 has a concentric recess 88 opening into the compression chamber 80,.'and

an axial passage 80 therethrough providing 'a communicationbetween the compression ohamber80 and the reservoir 82. The passage 80 is controlled by a gravity valve 92, held against the skirt of the movable piston `28 into the anvnular 'chamber 38, thence through the passages 26 in the wall of the cylinder |2 into that portion of the cylinder |2 forward of the piston 28, and thence past the 1two-way valvev I8, through the discharge port I6 and fluid pressure delivery pipe ||4 Vand its respective branches into the uid pressure actuated motors |16, causing energiza- 4 tion of the motors, resulting in actuation of the respective brakes.

Uponvattainin'g a predetermined pressure in the system, the cylinder'58 has movedsuillciently for the reduced-end portion 46 of the rod 42 on the piston 28 to enter the passage |06 and engage the ball valve |08, and thereafter as the cylinder 56 advances on its compression stroke displacement by aretaining ring 84 seated in a groove in the wall defining the recess 88.

As shown, the gravity valve includes a disk 98 Y slidable inthe recess 88 between the retaining ring 84 and the perimeter defining the passage 90. The disk has a plurality of openings '88 therethrough for the passage of fluid when the valve is open, and when the valve is closed the disk seats on a flexible washer |00 supported on the perimeter defining the passage 80 and effectively seals the openings 98 and also thev passage 00.

The disk 86 carries a valve 02 including a I valve chamber |04 having a port |08 providing a communication between the compression chamber 80 and the reservoir 82, and a ball valve |08 in the valve chamber for controlling the .port

urged to its seat by a spring ||0 interposed between the ball and a hollow plug ||2 secured in ,the valve chamber.

-A fluid pressure delivery pipe or conduit ||4 suitably connected to the discharge port |8 of the cylinder |2 has'branches connected respectively to fluid pressure actuated motors H6, preferably arranged in pairs, one pair for actuating the brakes associated with-the front wheels of the vehicle and another pair for actuating the brakes associated with the rear wheels of the vehicle. l

'I'he brakes preferred include. a fixed support or backing plate. ||8 adapted to be secured to tion of the drum.

-A A thrust rod |28 has one of its ends seated -in the socket 64 of the plug 82 secured in the head of the cylinder 56, and its other end pivthe applied force is transmitted 'therefrom through the fixed piston, the valve |02 and the ro`d 4-2 to the' piston 28, resulting in movement .of the piston 28.

Upon the initial movement of the piston 28,

the sealing cup closes the passages 26, and. therev after the pressure on the fluid is received by the piston 28,. As the pressure on the uid is transferred to the Piston 28,' the ball valve |08 is urged from its seat by the reduced end 461on the rod 42, and the fluid n the compression chamber 80 is displaced therefrom through channels 44 and port |06, past the valve-|08, into the reservoir 82. Becauseof the transfer of pressure on the fluid in the system from .the large fixed piston 1'8 to the small movable pistonl 28, an increasel of pressure on the uid may be attained without an increase ln the applied force.

Upon the conclusion of a braking operation, the foot pedal lever |28 is released, and is returned to vits retracted position under the influence of the retractile spring |32 carrying with it the thrust rod |28. This results in release of the cylinder 56, whereupon the cylinder is returned to'its'retracted position .under the, influence ofthe spring 88.` This movement Aof the cylinder 58 results in closing of" the'` ball valve |08 and opening of the gravity valve |02 so as to establish a communication between the compression chamber 80 and the reservoir 82 by way of the pasl ,nular chamber 88 and the passages 48 in the ,Y

sage 80.

During this operation the piston 28 is return- 'ing to its retracted position under the influence of the spring 54, and as the piston 28 returns to its retracted position a partial vacuum is created inthe cylinder |2 forward of the piston 28. This resultsl in drawing uid from the reserimir 82 past the gravity valve' 02 into ,the compression chamber 88, thence through the passages. in the skirt -of the piston 28, through the anheadof the piston 28, past the sealing cup 52 into that portion ofthe cylinder I2 forward of the piston, completely filling the cylinder, and simultaneously with this operation fluid is returning .to the cylinder I2 from the Vfluid'pressure otally attached ,to a foot pedal lever |28 mounted Aon a stub shaft |30 and connected by a' retractile spring |32 to a fixed support |84.

In a normal operation, upon depressing' the l foot pedal lever |28, force is transmitted therefrom through the thrust rod |28 to the cylinder.

56, resulting in movement of the cylinder on its compression stroke.

-Durlng the initial movement of the cylinder 58 on its compression stroke, the gravity valve |02 closes, and thereafter fluid in the compression chamber 80 forward of thefixed piston 1 8 is displaced therefrom through the ports Slin.

actuated motors ||8 under the influence of the 'retractile springs |24 connecting the shoes of the respective brakes.

This may result in thel cylinder l2 receiving a quantity of' fluid in excess of the quantity required to completely flll the cylinder, and under ,such condition the excess fluid is displaced therefrom through the passages 28, into the annular chamber 88, thence 'through the passages 58 into the compression chamber. and the reservoir 82 communicating therewith. It will be readily apparentfrom Figs.. 2 and 3 that the contour of slots 2t in the plane of the interior wall of cylinder l2 willbe elliptical and hence wear of the sealing cup 52 during travel thereof within the cylinder will be reduced to a minimum because the edges of the slots are angularly related to the cup.

Although this invention has been described in connection with certain specific embodiments, the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only by the scope of the appended claims.

Having thus described the various features ofl the invention, what I claim as new and desire to secure by Letters Patent is l. A iiuid pressure producing device comprising telescopic casings closed at their outer ends, the inner casing having a discharge port, the outer casing having a filling opening, a piston fxedly secured in the outer casing intermediate the ends thereof dividing the casing into a reservoir and a compression chamber, means engaging the closed end of the outer casing for moving the latter, and a reciprocable piston in the inner v casing actuated by the iixed piston after a predetermined movement of the outer casing.

2. A fluid pressure producing device comprising telescopic casings closed at their outer ends. means securing the casings together and providing for limited relative movement, means for filling vthe casings, a discharge port for the inner casing, a piston iixedly secured in the outer casing intermediate the ends thereof dividing the casing into a reservoir and a compression chamber, means providing communication between the reservoir and the compression chamber, means engaging the closed end of the outer casing for moving the latter, and a reciprocable piston in the inner casing actuated by the fixed piston after a predetermined movement of the outer casing,

3. A fiuid pressure producing device comprising telescopic cylinders closed at their outer ends, means securing the cylinders together and providing for limited relative movement, the outer cylinder having a filling opening, the inner cylinder having a discharge port, a fixed piston in the outer cylinderdividing the cylinder into a reservoir and a compression chamber, the fixed piston having a passage therethrough, a valve controlling the passage, and a reciprocable piston in the inner cylinder actuated by the iixed piston after a predetermined movement of the outer casing and having a part adapted to engage and open the valve.

4. A fiuid pressure producing device comprising telescopic cylinders closed at their outer ends, means securing the cylinders together and providing for limited relative movement, the closed end of the outer cylinder having a filling opening, a plug normally closing the opening, the

closed end of the inner cylinder having a discharge port, a fixed piston in the outer cylinder dividing the cylinder into a reservoir and a compression chamber, a valve in the fixed piston providing a. communication between the reservoir and the compression chamber, and a reciprocable piston in the inner cylinder actuated by I ing telescopic cylinders closed at their outer ends,

means securing the cylinders together and providing for limited relative movement, the closed end of the outer cylinder having a filling opening and a plug normally closing the opening, the closed end of the inner cylinder having a discharge port, a valve for control of the port, a

fixed piston in the outer cylinder dividing the cylinder into two chambers,` a sealing cup on the fixed, piston, a valve for control of an opening through the fixed piston, a sealing cup carried by the inner cylinder, a spring interposed between the cups, a reciprocable piston in the inner cylinder, a plunger carried thereby for tripping the valve in the iixed piston, the reciprocable piston having passages therethrough, a sealing cup on the reciprocable piston controlling the passages, means for by-passing fluid around the reciprocable piston when in retracted position, and a spring interposed between the sealing cup on the reciprocable piston and the valve controlling the discharge. port.

6. A iiuid pressure producing device comprising telescopic cylinders closed at their outer ends, means securing the cylinders together and providing for limitedrelative movement, the outer cylinder hav'ing a filling opening, the inner cylinder having a discharge port,a fixed piston in the outer cylinder dividing the outer cylinder into a reservoir and a compression chamber, a controlled passage through the piston, a sealing cup on the piston, a sealing cup carried by the inner cylinder, and a spring interposed between the cups.

7. A fluid pressure producing device comprising telescopic cylinders closed at their outer ends, the closed end of the outer cylinder having a filling opening, the closed end of the inner cylinder having a discharge port, means securing the cylinders together and providing for limited relative movement, a fixed piston in the outer cylinder dividing the cylinder into a reservoir back of the piston and a compression chamber forward of the piston, a sealing cup on the piston, a passage through the piston providing a communication between the reservoir and the compression chamber, a two-Way valve controlling the passage, a sealing cup carried lby the piston, a sealing cup carried by the inner cylinder, and a spring interposed between the cups.

8. A iiuid pressure producing device comprising telescopic cylinders closed at their outer ends, the closed end of the outer cylinder having a nlling opening normally closed by a plug, the closed end of the inner cylinder having a discharge port, a valve controlling the discharge port, a fixed piston in the outer cylinder dividing the cylinder into a reservoir back of the piston and a, compression chamber forward of the piston, a passageway through the piston, a two-way valve for control of the passageway, a sealing cup carried by the piston, a sealing cup carried by the inner cylinder, a spring interposed between the cups, a piston reciprocable in the inner cylinder actuatable by the fixed piston, controlled means for by-passing fluid through the reciprocable piston in one direction, means for by-passingv fluid 'past the reciprocable piston in both directions, and a spring interposed between the reciprocable piston and the valve controlling the discharge port.

9. A uid pressure producing device comprising telescopic cylinders closed at their outer ends, the outer cylinder having a. filling opening normally closed by a plug and the inner cylinder having adischarge port, a fixed piston in the I. 'passages therethrough, a sealing cup on the reciprocable piston controlling the passages therethrough, means for by-passing duidpast the re- 'ciprocable'piston in both directionswhen the piston is at rest, means carried by the reciprocable piston for tripping the valve in the fixed piston and for transmitting force from the iixed piston to th'e reciprocable piston, and a spring interposed between the cup on the reciprocable piston and the valve controlling the discharge port.

10. In a fluid pressure producing device, a large cylinder open at one of its ends and having a closure for its other end, means directly engaging the closure for actuating the cylinder, a fixed; piston in the' cylinder dividing the cylinder into 'a reservoir between the closure and the back of the piston and a compression chamber forward of the piston, a -controlled passage through the piston, and a relativelysmall cylinder telescoping the large cylinder having its inner end open and its outer end closed and provided with a discharge port.

trolled passage through the piston, a relativelysage, said piston dividing the outer cylinder into -a reservoir back of the piston and a compression 11. In a. iiuid pressure producing device, a. large cylinder closedat one end and open at its other end, the closed end having an opening, a plug for closing the opening having a socket for the 'reception of a thrust pin and openings for venting the cylinder,.a xed piston in the cylinder dividing' the cylinder into -two chambers, a consmall cylinder received by the large cylinder having its outer end closed and provided with a discharge port.' l 4 12-. In a fluid pressure producing device, a cylinder open at one end and closed at its other end,.the closed end having a discharge port, a

valve for control of the port, said cylinder having in its wall a plurality of "recesses, semielliptical in cross-section and also in longitudinal section, saidrecesses arranged in spaced relation 'and longitudinally ofthe cylinder, a piston reciprocable in the cylinder adapted toseat when at rest in the open end of the cylinder, a sealing cup on the head of the piston adapted to straddle the recesses when the piston is at rest, and a spring interposed between thesealing cup and the Valve. Y

- OWEN I.I. FOWLER. 

